434 ALASKAN GLACIER STUDIES
there is also a possibility of a southward shifting of the river bed, necessitating the building of another steel span.
From the point of view of tourists, who will undoubtedly make increasing use of the Copper River railway in the future, the location is ideal, for with no attendant danger or hardship, they can be carried by train almost up to the fronts of two very grand and active glaciers, both clearly visible from the train windows.
Qeneral Description. This ice tongue is on the western side of Copper River about half way between Childs and Allen Glaciers, terminating opposite the edge of Miles Glacier at the southern end of Abercrombie Rapids. It rises in unexplored snowfields at an elevation of at least 5000 or 6000 feet (PI. CLXIX) and flows southeastward, with a known length of something more than 4 miles. It is over three quarters of a mile wide and has a moderately steep slope. The surface of the glacier is all white, except for a broad lateral moraine on the southern border, a narrow medial moraine near the northern side, and an extensive area of outwash gravel and ablation moraine covering the terminus (PL CLXV).
The real terminus of Grinnell Glacier is in the Copper River (Map 9), at the lower end of Abercrombie Rapids, just south of Camp 52 on the Copper River and Northwestern Railway. The railway runs over the end of the glacier for nearly a quarter of a mile, but the terminal hill is so thickly covered with ablation moraine, on which dense thickets of alder and cottonwood have grown, that this portion of the ice tongue does not look like a glacier.
The southern portion of the glacier, terminating less than a quarter mile west of the railway, is also heavily covered with ablation moraine and forest, which grades northwestward to a barren region of thinner, ablation moraine and to clear ice without morainic covering.
The northern terminus of the clear ice, which seems to be the glacier terminus, but is not, ends a little over half a mile northwest of Camp 52, on the railway. From it a stream flows through the interior flat and through a narrow gorge between the high outer portion of the glacier and the mountain side, to Copper River. Another stream, emerging from the southern part of the glacier near a conspicuous, bare rock slope, from which the ice is completely melted, flows southeastward over a mile to the Copper River.
Previous Observations. This glacier was mapped by Hayes in 1891: and Witherspoon in 1900,* when it was also photographed by Spencer from the Miles Glacier portage. It was photographed by Mofnt in 1907 from near the same site as that occupied by Spencer, and was shown upon a later edition (Fig. 68) of Witherspoon's map.8 Witherspoon's original map (Fig, 58) shows the glacier more accurately than the later edition in which the forest-covered terminus of the glacier is omitted. Hayes' map is more like the later edition of Witherspoon's but it has the name moraine printed between the glacier
1 Unpublished map.
1 PI, n, facing p. 28, in Schroder and Spencer's Greology and Mineral Resources of a Portion of the Copper River Region, Alaska, House Doc. fi46, 56th Congress, 2nd Session, Washington, 1901. »PI. I in Bull. 374. U. S. Geol. Survey, 1909.